rc: fix segfault when SIGINT is received

Save the value of `runq' at the start of the function, so that the `pc'
update
at the end does work on that original value, and not on a probably
modified
value of `runq'.

fixes #14 http://code.swtch.com/plan9port/issue/14/

http://codereview.appspot.com/104066
1 file changed